• Screened 177 Chinese GDM women (FBG ≥5.1 mmoL/L) for GCK variants. • Identified 8 rare GCK variants in 9 individuals (1.9 % prevalence). • No confirmed GCK-MODY cases found among variant carriers. • Limited utility of FBG-based GCK-MODY screening in Chinese GDM. Accumulating evidence suggests maturity onset diabetes of the young (MODY) caused by GCK gene mutations ( GCK -MODY) is often misdiagnosed as Gestational Diabetes Mellitus (GDM) in pregnant women. This study investigated the prevalence and diagnostic value of GCK gene mutations in Chinese GDM patients. A retrospective analysis was conducted on 3394 pregnant women undergoing prenatal care or delivery at Beijing Jishuitan Hospital between April and December 2019. GDM was diagnosed in 474 women (14.0%) using the International Association of Diabetes and Pregnancy Study Groups (IADPSG, 2010) criteria via a 75 g Oral Glucose Tolerance Test (OGTT). Among these, 177 GDM patients with fasting blood glucose ≥5.1 mmoL/L underwent targeted GCK gene sequencing. Targeted sequencing identified eight rare GCK variants in nine individuals. None of the variant carriers met definitive diagnostic criteria for GCK -MODY. The prevalence of rare GCK variants in the screened GDM subgroup was 1.9% (9/474). The low prevalence (1.9%) of rare GCK variants and absence of confirmed GCK -MODY cases indicate limited utility of fasting glucose-based screening for GCK -MODY in Chinese GDM populations. These findings highlight challenges in distinguishing GCK -MODY from GDM through conventional glucose thresholds.
Feng et al. (Thu,) studied this question.